<?php

namespace LowCode\Support;

use Stringable;

class HelpJs implements Stringable
{
    /**
     * The JavaScript string.
     *
     * @var string
     */
    protected string $js;

    /**
     * Flags that should be used when encoding to JSON.
     *
     * @var int
     */
    protected const REQUIRED_FLAGS = JSON_HEX_TAG | JSON_HEX_APOS | JSON_HEX_AMP | JSON_HEX_QUOT | JSON_THROW_ON_ERROR;

    /**
     * Create a new class instance.
     *
     * @param  mixed  $data
     * @param int|null $flags
     * @param int $depth
     * @return void
     *
     */
    public function __construct(mixed $data, ?int $flags = 0, int $depth = 512)
    {
        $this->js = $this->convertDataToJavaScriptExpression($data, $flags, $depth);
    }

    /**
     * Create a new JavaScript string from the given data.
     *
     * @param  mixed  $data
     * @param int $flags
     * @param int $depth
     * @return static
     *
     */
    public static function from(mixed $data, int $flags = 0, int $depth = 512): static
    {
        return new static($data, $flags, $depth);
    }

    /**
     * Convert the given data to a JavaScript expression.
     *
     * @param  mixed  $data
     * @param int $flags
     * @param int $depth
     * @return string
     *
     */
    protected function convertDataToJavaScriptExpression(mixed $data, int $flags = 0, int $depth = 512): string
    {
        $json = static::encode($data, $flags, $depth);
        if (is_string($data)) {
            return "'".substr($json, 1, -1)."'";
        }
        return $this->convertJsonToJavaScriptExpression($json, $flags);
    }

    /**
     * Encode the given data as JSON.
     *
     * @param  mixed  $data
     * @param int $flags
     * @param int $depth
     * @return string
     *
     */
    public static function encode(mixed $data, int $flags = 0, int $depth = 512): string
    {
        return json_encode($data, $flags | static::REQUIRED_FLAGS, $depth);
    }

    /**
     * Convert the given JSON to a JavaScript expression.
     *
     * @param  string  $json
     * @param int $flags
     * @return string
     */
    protected function convertJsonToJavaScriptExpression(string $json, int $flags = 0): string
    {
        if ($json === '[]' || $json === '{}') {
            return $json;
        }

        if (str_starts_with($json, '"') || str_starts_with($json, '{') || str_starts_with($json, '[')) {
            return "JSON.parse('".substr(json_encode($json, $flags | static::REQUIRED_FLAGS), 1, -1)."')";
        }

        return $json;
    }

    /**
     * Get the string representation of the data for use in HTML.
     *
     * @return string
     */
    public function toHtml(): string
    {
        return $this->js;
    }

    /**
     * Get the string representation of the data for use in HTML.
     *
     * @return string
     */
    public function __toString()
    {
        return $this->toHtml();
    }
}
